Fuel injector



Dec. 17, 1957 w. G. MCCAIN 2,816,745

FUEL INJECTOR Filed April 25, 1955 FUEL INJECTOR William G. McCain,Brookline, Mass.

Application April 25, 1955, Serial No. 503,753

4 Claims. (Cl. 261-23) The present invention relates to improvements infuel injection system for internal combustion gasoline engines and moreparticularly to the adaptation of a low pressure fuel injection systemto present existing engines, in which a commercial form of low pressurefuel pump is employed, in the manner disclosed in prior United StatesLetters Patent No. 2,238,333, granted April 15, 1941, upon applicationof the present inventor.

The use of the low pressure fuel injection system of the prior patent,above noted, has many advantages over those systems employing higherfuel pressure, primarily because with a lower pressure a greater ease incontrol of fuel flow is obtained with less complicated fuel lines andmetering components. Accordingly, it is a purpose of the presentinvention to obtain the benefits of such low pressure system forinjection of fuel at each individual outlet of a plural outlet manifoldfor a multicylinder engine without the usual objectionable results inthe way of inefiicient idling and improper power fuel proportioningaction heretofore found in gasoline engines of such nature, asdistinguished from engines having a central carburetor with a singlepower jet serving for several cylinders.

Other objects are to simplify and improve generally the operation of amulticylinder internal combustion engine at the type employing any formof volatile liquid fuel.

While the invention is applicable to use with multicylinder engines manybenefits of the invention are obtainable in connection with singlecylinder engines or those in which the fuel for full power operation isintroduced under pressure at a point in an elongated manifold of the lowvelocity type as far away as may be necessary from a central air controlvalve while the fuel for idling is introduced as close as possible tothe air control valve.

In the attainment of the purposes set forth, the present inventionprovides a low velocity intake manifold for a multicylinder internalcombustion engine, which manifold is constructed with a central airinlet tube and a plurality of outlets, individual power nozzles beingmounted in the outlets, a central idling jet entering the inlet tubeclose to an air control valve in the inlet tube, and control connectionsare provided for stopping the flow of fuel to the idling jet when thepower nozzles are supplied with fuel. In this way the proportioning ofmixture of the engine in all its cylinders is not disturbed by unevenflow of fuel from the idling jet under full power operations. It is alsowithin the purview of the invention to stop the flow of fuel to thepower nozzles when fuel is supplied to the idling jet. The transitionfrom one condition of engine operation to the other is accomplishedreadily by linkage including a floating lever connected at three remotepoints, one to an idling jet fuel control valve, and another to a powernozzle fuel control valve, and a third to a vacuum controlled piston,the cylinder for which has impressed upon it the suction produced in themanifold. In this way the jet and nozzle leakage or dribble is kept frominterfering with the mixture proportioning both unice der idling andpower operating conditions in the engine to which the manifold isconnected.

These and other features of the invention will readily be apparent, ashereinafter described and claimed, when taken in connection with thefollowing detailed specification and the appended drawings, in which:

Fig. 1 is a perspective view, looking from the front and right side of aplural outlet manifold for a multicylinder internal combustion engineembodying the features of the present invention;

Fig. 2 is a detail perspective view, partly broken away and shown insection and in separated relation, on a larger scale than that of Fig.1;

Fig. 3 is a sectional view on a further enlarged scale of a power nozzlein an outlet to the manifold of Fig. 1; and

Fig. 4 is a sectional detail view of a fuel metering valve for the powernozzles.

The fuel injector shown in the drawings consists of a low velocity typeintake manifold for a multicylinder internal combustion engine, whichmanifold is formed with a central air inlet tube and a plurality ofoutlets, one for each cylinder, each outlet being provided with anindividual power nozzle mounted in its center. In the past a seriousdifliculty has been encountered in such manifold arrangement by reasonof lack of smooth flexible fuel and air proportioning regulation betweenidling and full power operation. When the fuel is supplied by powernozzles only without the use of a separate idling jet too much fuel isadmitted to each cylinder for smooth idling when an attempt is made toregulate accurately at each nozzle, the nozzles being too large forproper atomization with small amounts of fuel required in smooth idling,especially when high fuel pressures are employed. Neither is itdesirable to depend for control of fuel in such manifolds upon air flowwith vacuum regulated fuel valves connected to Venturi restrictions inthe inlet, since restrictions interfere with free flow of air in a lowvelocity manifold under high power requirements. With interference offree air flow the greatest benefits of individual fuel injection systemsare defeated. Thus, in the present system the full benefit of a lowvelocity intake manifold with fuel injection is retained by the use ofmechanical mixture regulating connections between an air control valvein the manifold inlet and a fuel control valve for the power nozzles,the arrangement including connections for admitting flow of fuel to anidling jet mounted in the air inlet tube in close proximity to the aircontrol valve when the air control valve is closed and for stopping flowof fuel to the idling jet when the air control valve is opened. In thisway the problem of regulating the flow of small amounts of fuel throughrelatively large power nozzles without proper atomization is avoided.Furthermore, the additional problem of power nozzle dribble, commonlyafflicting prior fuel injector systems is avoided, whether the system isprovided with central power and idling controls or, in the case of thepresent system with individual power nozzles at the outlets of themanifold. The mechanical connections also act on a power controlmetering valve for closing it when the fuel flows through theidling jet.

Referring more particularly to the drawings, the manifold is indicatedat 11, the inlet tube at 2, the air control valve including a shaft 3and a vane 4 on the shaft and the mechanical connections including anoperating arm 5, a sector shaped cam 6 pivoted on a fixed fuelconducting block 16, a roller 7 rotatable at one end of a lever 8, inturn, rotatable loosely on a horizontal shaft 9 and a spring 10compressed between the lever 8 and an angular arm 11 (see Fig. 2)secured to the shaft 9. The arm 5 is connected to the earn 6 by a link36 pivoted at its ends on screws threaded into the arm and cam. Theshaft 9 has fixed on its central portion the hub of a forked arm 12 andis rotatable in ears extending horizontally from the inlet tube 2 in themanifold. Within the fork of the arm 12 is a metering pin 13 having ahead beneath which the fork of the arm 12 acts as a control for powerfuel supply. The pin 13 and a seat in the block 16 form the valve forthis purpose and the pin enters a sleeve 130 rising from the block toopen or close a lengthwise passage therein by which the fuel enters. Thepassage is indicated at 37 and bypasses the power fuel control valve tosupply fuel to the idling jet, as will be described. Surrounding the pin13 is a coil spring 27 confined by a shoulder at the upper end of thesleeve 130 and disposed to hold the power valve closed yieldingly. Theconnections thus described are arranged to open the power fuel controlvalve when the air control valve is opened and to close the power control valve when the air control valve is closed.

The power fuel control valve feeds fuel from the con ducting block'16through'passageways 17 in aT-shaped side projection 15, there beingone'projection at either side of the block 15. Through the projectionsof the block fuel is fed in opposite directions from the main bodyportion of the block to the various cylinders of the engine by way of aseries of tubes 18 running to the projections from each of a series ofindividual power nozzles 26, one being mounted in the center of eachmanifold outlet directly above each intake valve.

The mixture regulating connections also include idle fuel valvecontrols. Whereas, the roller 7 engages a more or less radial surface onthe sector shaped cam 6, an arcuate surface of the cam has a recess andis arranged to be engaged by a second follower roller 35 rotatablymounted at one end of a lever 34 acting on the idle fuel valve,comprising a pin 31 and a seat in the block 16 into which the pin 13enters. Lifting pin 31 from its seat causes fuel to fiow from thepassage 37 to an idling jet 33 past an idling adjustment screw 32 of theusual form. To lift the pin 31 from its seat the lever 34 is fixed to ahorizontal shaft 29 rotatable in the ears of the manifold inlet tube 2.Also fixed to the shaft 29 is a forked arm surrounding the upper end ofthe pin 31 beneath a head engaged by the arm 30. Surroundingthe pin 31is a coil spring 27 confined by a shouldered upper end of a sleeve 2330rising from the block 16. The spring 27 acts to hold the idle fuelvalve-normally closed but when the recess in the earn 6 moves under theroller the idle fuel valve is opened by suction in the manifold inlettube 2. The arrangement of'the idle fuel valve connections is such thatflow of fuel is admitted to theidling jet when the air control valve 4is closed and the idle fuel valve is closed when the air control valveis opened. This occurs when the power fuel control valve is opened withthe opening of the air control valve. The idling jet 33 is located inthe inlet tube 2 in close proximity'to the air control valve 4 wherethere is a maximum of turbulence in the air so that thereis no necessityfor a Venturi restriction in the inlet tube.

To assist in opening and closing the power and idle fuel control valvesthe shaft'9 has secured to it an arm 19 pivotally connected through alink 20 to a point at one end of a floating lever 23'capable of freebodily movement. The floating lever 23 has another point at its otherend pivotally' connected to a link'280 also pivotally connected to anarm 28 secured to the shaft 29, the action being such that the floatinglever 23 is movable about any one of three separated points along itslength as a fulcrum. The third point along the lever is at anintermediate location where a pivotal connection is made with a piston'22 sliding within a cylinder 21. The cylinder 21 is connected'by a tube24 with the air inlet tube 2 of the manifold below the air control vane.Thus when the air control valve is nearly closed by theva'ne a strongsuction or vacuum acts through the tube 24 to draw the piston downwardlyinto the cylinder, causing the shaft 9 to be rotated against the actionof the spring 10 in a direction to close the power fuel control valve.The suction also tends to open the idle fuel valve by raising the pin 31from its seat in the conducting block 16. if the cam 6 is moved to aposition where the roller 5 fits within the recess of the cam the idlefuel valve is positively opened by the suction in the cylinder 21 andthe engine to which the manifold is attached is operated at idlingspeed. If the pressure in the manifold should decrease by reason of anengine speed reduction, the shaft 9 is rotated by the spring 10 toinject a small additional amount of fuel through the power fuel controlvalve. This additional fuel increases the engine revolutions suffcientlyto restore the idling speed and the vacuum within the manifold. In thisway a particularly stable speed regulation is obtained in the engineunder idling conditions.

With the air control vane 4 nearly closing the air control valve and theengine to which the manifold is connected idling, fuel flows through theidle fuel valve, past the pin 31, which acts to meter the idle fuel, thepin disengaging its seat in the block 61. The vacuum in the manifoldholding the pin away from its seat is limited in the amount of movementwhich it imparts to the pin by the depth of the recess in the peripheryof the cam 6, the roller floating within the recess to a certain extent.It will be noted that the forked arm 30 extends to the same side of theshaft 29 as does the forked arm 12 on the shaft 29, but that the arm 28is on the opposite side of the shaft 29 from that at which the arm 19projects from the shaft 9. Thus, the suction in the manifold tends toopen the idle fuel control valve but tends to cause the power fuelcontrol valve to close. When the engine is operating under full powerthe reverse is true, any decrease in manifold suction or degree ofvacuum causing the idle fuel control valve to close and the power fuelcontrol valve to open under the action of the spring 10.

When the engine comes to rest and no suction exists in the manifold boththe idle and power fuel control valves are closed by their respectivesprings, the strength of the spring 10 being insufiicient to open thepower fuel valve when the air control valve is closed and the arm 5 andthe cam 6 are moved to the extreme right as they normally would be whenthe engine is stopped. Thus, there is no leakage of fuel from thesevalves when the engine operation is discontinued.

The' nature and scope of the invention having been indicated, and aparticularly defined embodiment having been described, what is claimedis:

1. A fuel injector for an internal combustion engine, having'a lowvelocity intake manifold with a central air inlet tube and a pluralityof outlets, an individual power nozzle mounted in the center of eachmanifold outlet, an air control valve in the inlet tube, a fuel tuberunning from each power nozzle,-a power fuel control valve connected toall the fuel tubes, mixture regulating connections including a cam and afollower roller between the air control valve and the fuel control valveto change the fuel supply to the nozzles as the air control valve isopened or closed, an idling jet entering the air inlet tube, and an idlefuel valve for controlling the flow of fuel to the idling jet, incombination with idling connections including a second followerrolleracting on said cam and having a lever acting on the idle fuel valve foradmitting flow of fuel to the idling jet when the air control valve isclosed and for closing the idle fuel valve when the air control valve'is opened.

2. A fuel injector for an internal combustion engine, havinga lowvelocity intake manifold with a central air inlet tube and a pluralityof outlets, an individual power fuel-nozzle' mounted in each manifoldoutlet, an air control valve'in the 'ihlet tub'e, a fuel tube runningfrom each power nozzle, a power fuel control valve connected to all thefuel tubes, mixture regulating connections between the air control valveand the power fuel control valve to change the fuel supply to thenozzles as the air control valve is opened or closed, an idling jetentering the air inlet tube, and an idle fuel valve for controlling theflow of fuel to the idling jet, in combination with idling connectionsbetween the air control valve and the idle fuel control valve foradmitting flow of fuel to the idling jet when the air control valve isclosed and for stopping the flow of fuel to the idling jet when the aircontrol valve is opened, and manifold vacuum controlled means tending toopen the idle fuel control valve and to close the power fuel controlvalve upon increased suction in the manifold.

3. A fuel injector for an internal combustion engine, having a lowvelocity intake manifold with a central air inlet tube and a pluralityof outlets, an individual power nozzle mounted in each manifold outlet,an air control valve in the inlet tube, a fuel tube running from eachpower nozzle, a power fuel control valve connected to all the fueltubes, mixture regulating connections between the air control valve andthe power control valve to change the fuel supply to the nozzles as theair control valve is opened or closed, an idling jet entering the airinlet tube, and an idle fuel valve for controlling the flow of fuel tothe idling jet, in combination with idling connections be tween the aircontrol valve and the idle fuel control valve to change the fuel supplyto the idling jet when the air control valve is opened or closed, andmanifold vacuum controlled means tending to close the idle fuel controlValve and to open the power fuel control valve upon decreased suction inthe manifold.

4. A fuel injector for an internal combustion engine, having a lowvelocity intake manifold with a central air inlet tube and a pluralityof outlets, an individual power fuel nozzle mounted in each manifoldoutlet, an air control valve in the inlet tube, a fuel tube running fromeach power nozzle, a power fuel control valve connected to all the fueltubes, mixture regulating connections between the air control valve andthe power fuel control valve to change the fuel supply to the nozzles asthe air control valve is opened or closed, an idling jet entering theair inlet tube, and an idle fuel valve for controlling the flow of fuelto the idling jet, in combination with idling connections between theair control valve and the idle fuel control valve for admitting flow offuel to the idling jet when the air control valve is closed and forstopping the fiow of fuel to the idling jet when the air control valveis opened, and manifold vacuum controlled means tending to open the idlefuel control valve and to close the power fuel control valve uponincreased suction in the manifold, said idling connections including afloating lever connected at one point to the power fuel control valveand at another point to the idle fuel control valve, a cylinderconnected to the manifold and a piston connected to a third point on thefloating lever tending to open the idle fuel control valve upon increasein manifold suction and to close the power fuel control valve when thedegree of vacuum is decreased in the cylinder.

References Cited in the file of this patent UNITED STATES PATENTS2,150,081 Schorsch Mar. 7, 1939 2,313,366 Schweir Mar. 9, 1943 2,320,012Riall May 25, 1943 2,428,377 Morris Oct. 7, 1947 2,502,679 Stanly Apr.4, 1950 2,611,595 Streed Sept. 23, 1952

